Conventional vehicle support frames can be composed of different materials including, for example, steel, aluminum and reinforced polymer composites. Vehicle manufactures attempt to strike the balance between weight reduction and structural rigidity. It is desirable to design lightweight cross-members for full-sized light truck frames. Aluminum cross-members can be designed to achieve up to 50% weight reduction while still meeting performance targets. Though aluminum cross-members have high potential for building lightweight truck frames aluminum has a lower material strength than steel. Joining aluminum members to steel frame rails also present challenges especially when both parts are closed-section tubular components. Additionally, it can be costly to retool existing manufacturing facilities handle complex techniques of joining dissimilar materials.
Some existing references within the art teach the use of mechanical fasteners to secure two rails made of dissimilar materials together. These techniques, however, are less desirable. These mechanical features include fasteners, which can increase costs and manufacturing complexity. One patent reference teaches the use of an overlapping configuration for the rails of dissimilar materials. A structural member sandwiches one end of a first structural member and is welded onto a second structural member. US Patent Publication No. 20090188206, titled “System and Method for Joining Dissimilar Materials.” The overlapping configuration taught therein forms for a 3-way mechanical interlock and is more suitable for collinear structural member connection as opposed to intersecting or angled structural member connection, i.e., side rail to cross-member connections. Closed-section structural members also appear to be incompatible with these teachings.
Therefore, it is desirable to have improved interconnecting techniques for joining two structural members composed of dissimilar materials to produce a vehicle frame assembly.